Observing a solar eclipse

Last Friday (20/03/2015) central Europe could observe a partial solar eclipse.

Partial solar eclipse on March 20th, 2015 (photo: Belfast Telegraph)

Partial solar eclipse on March 20th, 2015 (photo: Belfast Telegraph)

Solar eclipse always require, on the astronomers side, big campaigns to tell people how to observe the phenomenon, otherwise they will look directly into it, or worse, point binoculars, cameras and telescopes at it … and get permanently blinded …

The best approach are the campaigns with special goggles, made of a protective film, that cuts 99.999% of the visible light and specially infra-red and ultra-violet light. Of course those goggles are sold out quite quickly, some weeks before the eclipse.

One gets home, the night before the eclipse and there’s a letter from school asking authorization for my kid to go outside and observe the eclipse and asking for the protective glasses, and if possible more than one. Great. How am I going to get something out of business hours that is already sold out for weeks?

With some notice I could have revived the solar projector I did in college for the 1993 solar eclipse back in Brazil and built with the school kids. Simple project: lenses for glasses, pipe to hold and focus the lenses and a mirror to direct the sun light into it.

Too late! So the option was the “shoeboxpinholeinator”!!! (OK, OK, when you have young kids you watch a lot of Disney Channel :-P ) So, the last minute option was to build a shoebox pinhole camera.

Basically get a shoebox, cut an opening on one side, cover it with some aluminium paper and pinhole it. On the other extreme put some white paper, as projection screen. Cut a side opening to be able to see the projection on the white screen, while keeping it mostly in the dark. Close the box, sealing possible light leaks and it’s done.

Me and my son have been experimenting with pinhole cameras recently. As an astronomer and amateur photographer I like a lot the optical part of it and try to bring home some interest in it.

At the end, he took the camera to school (they had collected enough protection goggles anyway) and used it to observe. And me as daddy couldn’t be more proud ;-)

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Canon ESO 60D – From Snapshots to Great Shots

Coming back from a very long time off. A complex setup of personal and professional changes simply took all my time leaving nothing to be used in photography in any way. Sad but true.

Now things come back to a manageable state, so I can start coming back to writing, at least :-)

Canon 60D - From snapshots to great shots - Nicole S. Young

Canon 60D – From snapshots to great shots – Nicole S. Young

In this period a book came to my hand and manage to finish reading it: “Canon ESO 60D – From Snapshots to Great Shots” from Nicole S. Young. Nicole is a great photographer and recently has been involved in several projects I’ve been following. She’s the author of the “Food Photography” book of this series, and also the one for the 7D and 70D Canon ESO cameras.

The Canon EOS 60D (and now the 70D) is labelled as a “prosumer” camera and that fits a couple of profiles. The “I really like photography, but can’t afford a full frame camera and the cost of full frame lenses”. The “I used to photograph in the past and would like to come back, but I don’t want to spend a bunch of money before I’m sure”. The camera has a nice look and feel, at least for my size of hand. They didn’t save in buttons and dials, so you can have a good level of control without too much effort, more like a pro camera.

When I first saw the book I thought on something like “a secret user’s manual for my camera”, cool. The book is more a book about photography, from the basic concepts of composition and exposure triangle, to some more “advanced” stuff.

Then, the question is, why is it a book for 60D users? It’s not entirely. It’s a book that is useful to anyone starting/restarting in photography that wants to improve. The 60D part comes into play because the book shows “how do you do this part that I’m teaching you in a 60D”. For example: talks about ISO and it tells you how to change the ISO in the 60D. Talks to you about “aperture priority” and tells you how to put the 60D in aperture priority mode and how to control it.

In addition, the book brings a set of challenges at the end of each chapter that may or not be directly related to how the camera works, but always a nice photography exercise.

I don’t know if other “camera specific” books from this series have this kind of content and are that good, but this is surely a recommended reading to anyone with a prosumer level Canon camera and possible to anyone willing to learn some nice basics of photography in a didactic and well written way.

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Experimenting with Timelapses

We all have seen those great timelapses of night ski and other beautiful stuff.

Timelapse - Moonrise (Photo: Cris Da Rocha)

Timelapse – Moonrise (Photo: Cris Da Rocha)

Recently Kelby One released a class with Tom Bol that really puts the thing in very simple terms (how to shoot, which software to use to process and make the final movie).

Since then I have been looking for opportunities to try some timelapse. Did some testing with drawings (the classic Mary Poppins sketch flying with an umbrella …) and this last weekend I saw a great moonrise just in front of my balcony and it came “that’s it! the first try!”. Next day I was ready for it.

Adventure starts :-) Check the moonrise time (as an astronomer I know those things change daily hehehehehe), internet is full of sites that tell you that.

Checked the typical interval for a moonrise timelapse. Each subject has its timing. Apparently sun and moonrise would be something like a shot every 3 seconds.

Got everything nice and ready, estimated the shutter speed, manual mode and so on. Since I don’t have an intervalometer (not buying one just for the idea) and my camera doesn’t have it inside, I used my IR remote control. Should work. Just decided to go on a 5 seconds interval, since I would have to trigger each single frame.

Moon didn’t appeared when it was supposed to. 50 minutes later, sky was darker and the moon started to make it brighter. In those 50 minutes I went updating my shutter speed, ISO and so, to make exposure X noise reasonable.

Since I was not sure the moon was actually coming I started with a 10 seconds interval, when it started to show I moved to a 5 seconds interval, but got tired after a while of pressing the remote so I moved back to 10 seconds, which seemed reasonable in the back of the camera. The moon was not moving thaaaat fast in the sky.

I chose a very wide angle, to get the sky and some of the roofs. After 30 minutes I was tired of pressing the remote (I had 217 shots) and the moon was only slightly above the roofs. Then I got into my scientific self to realize it would take A WHILE for the moon to reach the edge of my frame :-) So I called it a day with the thought “I can crop it in”.

Back in, imported in Lightroom and I took Tom Bol’s advice and decided to test LR Timelapse, amazing “plugin” for LR (quoted because is sort of a stand-by tool that uses Lightroom for control and making the output images).

LR Timelapse, for the simple use could not be simpler and more instructive. I would not say it’s intuitive (since you have to go back and forth to Lightroom) but it’s instructive, it tells what to do next! No doubts about it.

At the end you’re left with a video file!!

The “tricky” point was to make the different time intervals work together. My approach was to break the sequence in 3 parts (the beginning at 10 second/frame interval, the middle at 5 second/frame and the end again at 10 second/frame). The middle part was rendered at normal speed and the beginning and end at 1/2 speed, so the real time rate was the same.

After having the three videos I merged them at Photoshop and I had nice in 1080p :-)

But the movement of the moon in the frame is quite small, on the other hand the movement of clouds, stars and planes in the sky and also the lights in the neighbors’ windows and the light decay are really nice (it’s in my balcony every night, but I never really cared to notice it :-) ).

The next option was to crop the frames in get a significant movement of the moon in the frame. With an 18Mpix camera I could really crop it and still get enough pixels for a 720p video!

The moon movement is nice and more impressive, but you loose the other features in the sky. It’s a compromise. Probably the next approach would be to get wide angle still, but with a larger time rate (10 or even 15 seconds/frame) and do it for a couple of hours. For that, an intervalometer becomes a must be, so now I’m looking into it :-)

Well! Let me know your impressions and experiences in the topic!!!

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Just a short note on DEDPXL, amazingly busy couple of weeks (but I really liked Zack’s project!).

DEDPXL assignment #02 - Shapes 04

DEDPXL assignment #02 – Shapes 04

The critique for assignment 02 is out, quite long, but worth watching the long version (in 3 parts). Unfortunately none of my shots made it. Let’s see next time (gotta find time and inspiration to shoot).

The next assignment (03) is out and is about Shadows! Already saw some stuff on Google+ about it. Some are very nice, some … could be way better. The shot above from the previous assignment could be an option for shadows also, but I have to redo it, or do something better.

Have fun!

Link for DEDPLX03.

Link for the short version of the critique (that has the links to the long version – wanted to refer back to the DEDPXL website, instead of embedding youtube videos).

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Sensor size X Depth of field

More often than not you see the discussion on how the sensor size affects the depth of field and I really can’t see that, since the light doesn’t know where it’s gonna land (if a full frame, an APS-C, a micro four-thirds …). So I think there’s a big misconception on the topic.

Depth of Field, a nice tool (photo: Cris da Rocha)

Depth of Field, a nice tool (photo: Cris da Rocha)

Having said that, I tried to understand where does that come from. I packed that with the concept of “zoom” for smaller sensors and equivalent focal length (and now the recent argument of equivalent aperture).

Being a bit hard on that, but … the difference between full frame and APS-C (for example) is the sensor size. The image is not magnified (in the optical sense), your image is cropped!!!

What you see in your APS-C sensor (Nikon flavor) with a 50mm at f/4 is the same you’d see in a full frame sensor with a 75mm at f/6 (that’s the “equivalent” number you’re using, keep the reduction of aperture in mind also). OK! But that doesn’t mean you are using a 75mm at f/6 you’re using a 50mm at f/4.

Comparison between the field of view of a full frame sensor and an APS-C sensor. (Photo: Cris da Rocha)

Comparison between the field of view of a full frame sensor and an APS-C sensor. (photo: Cris da Rocha)

Most of the available comparisons I see around rely on recompose the shot, or zoom in, so the content in the image is the same, but the camera specs change (for example one is at 50mm, other is at 75mm, and so on). Once you move the camera, or zoom in, all the relative distances or internal specs are different and the comparison is no longer fair!

After some discussion with several friends I partnered with one of them, Vincenzo Forchi, that happens to have a Nikon FX (full frame) camera and a Nikon DX (APS-C) camera, so we could make the test using the very same lens.

The shots were taken at the SAME DISTANCE from the subject, so no recomposing.

We took the same shot with different configurations:

1- Full frame camera at 50mm f/4
2- DX mode (which reduces the used area to a APS-C size) with the full frame camera at 50mm f/4
3- Full frame camera at 75mm f/7.1 (to emulate the “equivalent” of a DX camera)
4- APS-C camera at 50mm f/4

For technical reasons we lost the shot for 75mm f/4.

Can’t see the difference between the shots.

They all use an aperture that has the physical size of about 12.5mm and that’s what light cares about.

FF sensor in FX mode @50mm f/4 (photo: Vincenzo Forchi)

FF sensor in FX mode @50mm f/4 (photo: Vincenzo Forchi)

FF sensor in DX mode (cuts down to APS-C size in camera) @50mm f/4 (photo: Vincenzo Forchi)

FF sensor in DX mode (cuts down to APS-C size in camera) @50mm f/4 (photo: Vincenzo Forchi)

FF sensor in FX mode @75mm f/7.1 (photo: Vincenzo Forchi)

FF sensor in FX mode @75mm f/7.1 (photo: Vincenzo Forchi)

APS-C sensor @50mm f/4 (photo: Vincenzo Forchi)

APS-C sensor @50mm f/4 (photo: Vincenzo Forchi)

Any thoughts about it?? Please share!

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